The decentered magnetic dipole: a challenge for modelling

The global bipolar structure of the magnetic surface field is asymmetric for many stars, making its analytical description by an expansion of spherical harmonics problematic because of the coordinates. Landstreet (1970) proposed that the asymmetry could be understood assuming a decentered magnetic dipole in the stellar interior. Its surface field can be calculated for different arrangements inside and outside the star using the Magnetic Charge Distribution method. We demonstrate the effect for the two cases of the shift of the dipole along and perpendicular to the radial direction.